Hitherto, light-weight portable image pick-up apparatuses such as digital still cameras and video cameras have become popular. Since such small-sized image pick-up apparatuses are small and light in weight, but poor in stability, unwanted movement and/or vibration during picture-taking (hereinafter simply referred to as hand movement) is apt to take place.
In view of the above, small-sized image pick-up apparatuses capable of correcting such hand movement have been used. The hand movement correction is performed by detecting hand movement quantity (direction and magnitude of hand movement) and using the movement quantity to correct for image movement or shaking.
As a method of detecting hand movement quantity, there is mentioned a method in which an angular velocity sensor for detecting angular velocity in a vertical direction and an angular velocity sensor for detecting angular velocity in a horizontal direction are provided at a small-sized image pick-up apparatus, the detected angular velocities being used to detect hand movement quantity. In addition, there is mentioned a method of extracting components necessary for detection of hand movement quantity from an image signal of a previous frame and an image signal of a current frame, wherein hand movement quantity is detected by a representative point matching method, etc.
As a method of correcting image movement or shaking, there is mentioned a method in which a variangle prism (hereinafter referred to as VAP) is provided at a small-sized image pick-up apparatus to change the optical axis in accordance with detected hand movement quantity. However, when a VAP is provided at the image pick-up apparatus, miniaturization of the image pick-up apparatus is difficult because the lens unit becomes large.
On the other hand, as a method that lends itself to miniaturization of the image pick-up apparatus, there is mentioned, as shown in FIG. 1, the so-called electronic hand movement correction system in which there is provided a CCD (Charge Coupled Device) 200 having a region constituted by effective pixels (hereinafter referred to as effective pixel region) Y which is broader than an image generation region X from which an image signal finally serving as an output image is generated. The image generation region X is moved relative to the effective pixel region Y to thereby correct image movement or shaking by hand movement The electronic hand movement correction system prevents the shifting of frames due to the influence of hand movement, thereby generating images in which hand movement has been corrected.
Meanwhile, there are increasing numbers of image pick-up apparatuses capable of picking up both moving pictures (images) and still images. However, in the case of a still picture (image), when hand movement takes place within exposure time, image movement or shaking takes place because a picture signal which has been corrupted by hand movement is outputted from the image pick-up element.
However, in an electronic hand movement correction system, it is impossible to correct influence of hand movement during exposure. Namely, a small-sized image pickup apparatus employing an electronic hand movement correction system amendable to miniaturization cannot sufficiently correct for hand movement that occurs during generation of a still picture (image).
In view of the above, an image pick-up apparatus employing electronic hand movement correction provides improvement in picture quality in the case of moving images as compared to still images.
Further, in image pick-up apparatuses, there are instances in which a manual focus control function for manually controlling the focal point is provided along with an electronic hand movement correction function. As shown in FIG. 2, when an image pick-up apparatus 201 having a manual focus control function along with an electronic hand movement function picks up an image of a still picture, CCD 200 converts the optical image which has passed through a lens portion 211 into an electrical image signal. Then, the image signal outputted from the CCD 200 is converted into a digital signal by an analog front end 212. Further, an image signal processing unit 213 processes the image signal outputted from the analog front end 212. The image signal processed by the image signal processing unit 213 is once recorded into a memory 214, and is then displayed on a display unit 216 in accordance with a display control unit 215. The user operates a manual focus control unit 217 while observing the image displayed on the display unit 216 to thereby manually control the focal point.
Further, there are instances in which the image pick-up apparatus 201 performs an auxiliary function to enlarge the image displayed on the display unit 216 during focal point control. When the image is enlarged by the auxiliary function, a microcomputer 218 first sets an enlarged image generation region W within image generation region X as shown in FIG. 1. Further, the microcomputer 218 controls a timing generator (hereinafter referred to as TG) 219 to control the output of image signal from the CCD 200, or to control the read-out of image signal from the memory 214 so as to deliver an image signal corresponding to enlarged image generation region W to the display control unit 215. The display control unit 215 prepares an enlarged image of a predetermined size based on the delivered image signal and displays the enlarged image on the display unit 216. When the enlarged image is displayed on the display unit 216 during manual focus control, it is easier for the user to visually assess the effect of arbitrary focus control.
However, a moving picture (image) displayed on the display unit 216 is sensitive to hand movement. That is, since the image is enlarged, the image movement or shaking becomes large. Moreover, since hand movement correction is not performed when a still image is picked up, the enlarged image generation region W is set at a predetermined position even if hand movement takes place. Therefore, the image displayed in the enlarged state on the display unit 216 has large image movement or shaking and it becomes difficult for the user to observe the image displayed on the display unit 216 when performing focus control. Thus, although an enlarged image is displayed on display unit 216 for the purpose of facilitating execution of focus control, it becomes difficult for the user to perform arbitrary focus control.
Further, in the image pick-up apparatus 201, image controls such as focus control, white balance control and/or exposure control, etc. are performed on the basis of an image signal corresponding to a predetermined area of the light receiving surface of CCD 200 (hereinafter referred to as control signal generation region Z). The control signal generation region Z moves by the same distance in the same direction as that of the image generation region X. As the result of the fact that the control signal generation region Z moves by the same distance in the same direction as that of the image generation region X, the effect of hand movement on focus control, white balance control and/or exposure control, etc. is reduced.
However, in the image pick-up apparatus 201, since hand movement correction is not performed when an image of still picture is picked up, the image generation region X is not moved. Therefore, the control signal generation region Z is not moved.
Accordingly, the image signal outputted from the control signal generation region Z is corrupted by hand movement. Namely, in the image pick-up apparatus 201, since white balance control, and/or exposure control, etc. are performed on the basis of an image signal that is corrupted by hand movement, it becomes difficult to suitably perform white balance control and/or exposure control, etc. Accordingly, still picture (image) obtained by the image pick-up apparatus is corrupted.